Vehicle air conditioning system is a term used broadly enough to encompass both heating and cooling of interior air, as well as ventilation and defrosting of windshields. A typical system incorporates an evaporator core connected to a compressor and a heater core connected to the radiator, both secured inside a box like housing. Most commonly, the evaporator core is situated just behind the fresh air intake, and in front of the heater core. Therefore, all fresh air drawn into the system passes through the evaporator core first, regardless of whether the system is in a cooling or heating mode. In the heating mode, no refrigerant circulates in the evaporator core, so there is no cooling of the air even though it passes through it. While heated radiator coolant circulates continually in the heater core, a door within the housing controls temperature by deflecting air either totally or partially away from the heater core. At least two other movable doors are also needed within the housing for so called mode control, that is, for directing air into physical ducts that empty onto the windshield, toward the floor, or more directly at a vehicle occupant. These doors all need separate controls and actuators, which consumes space, has additional part count, and assembly cost.